Field of the Disclosure
This application generally relates to force sensing using frustrated total internal reflection (FITR) and capacitive techniques, and other matters.
Background of the Disclosure
Touch devices generally provide for identification of positions where the user touches the device, including movement, gestures, and other effects of position detection. For a first example, touch devices can provide information to a computing system regarding user interaction with a graphical user interface (GUI), such as pointing to elements, reorienting or repositioning those elements, editing or typing, and other GUI features. For a second example, touch devices can provide information to a computing system suitable for a user to interact with an application program, such as relating to input or manipulation of animation, photographs, pictures, slide presentations, sound, text, other audiovisual elements, and otherwise.
It sometimes occurs that, when interfacing with a GUI, or with an application program, it would be advantageous for the user to be able to indicate an amount of force applied when manipulating, moving, pointing to, touching, or otherwise interacting with, a touch device. For a first example, it might be advantageous for the user to be able to manipulate a screen element or other object in a first way with a relatively lighter touch, or in a second way with a relatively more forceful or sharper touch. In one such case, it might be advantageous if the user could move a screen element or other object with a relatively lighter touch, while the user could alternatively invoke or select that same screen element or other object with a relatively more forceful or sharper touch. For a second example, it might be advantageous for the user to be able to provide input in multiple ways depending in an amount of touch, such as a first way for a light touch, a second way for a medium touch, and a third way for a heavy touch. Similarly, “multiple ways depending in an amount of touch” might include any particular number of ways, that is, not just two or three. For a third example, it might be advantageous for the user to be able to provide input with an analog control in response to an amount of force, such as a gas pedal on a simulated car, or a control surface of an airplane in a flight simulator. For a fourth example, it might be advantageous for the user to be able to provide input, such as simulated body movements or otherwise, in a virtual reality (VR) simulation (possibly with haptic feedback), or in an augmented reality program.
Some touch devices are able to determine a location of touch, or multiple locations for more than one touch. For example, the Multitouch 3200, marketed by FlatFrog Laboratories AB of Lund, Sweden, uses “Planar Scatter Detection” technology. Light is injected into a waveguide, travels via total internal reflection within the waveguide, and is disturbed by an object (such as a finger) touching the waveguide, resulting in FTIR (“Frustrated Total Internal Reflection”), from which the location of the touch can be determined by software. Light can also be scattered by the touch, which might also provide a source of information about the touch. For example, a tabletop touch product called “Surface”, marketed by Microsoft Corporation of Redmond, Wash., includes an FTIR tabletop, with cameras mounted behind it that detect light refracted by pressure.
RAPT Technology of Dublin, Ireland also markets a touch-sensitive input device. Perceptive Pixel, owned by Microsoft Corporation of Redmond, Wash., markets a multi-touch sensing device that uses FTIR, and which is said to use a force-sensitive technique. Peratech, of Rich-mond, UK markets a technology that uses a “quantum tunneling composite” material, which has a variable resistance in response to pressure, using a polymer embedded with spiky conductive metallic particles.
Each of these examples, as well as other possible considerations, can cause one or more difficulties for the touch device, at least in that inability to determine an amount of force applied by the user when contacting the touch device might cause a GUI or an application program to be unable to provide functions that would be advantageous. When such functions are called for, inability to provide those functions may subject the touch device to lesser capabilities, to the possible detriment of the effectiveness and value of the touch device. On the other hand, having the ability to provide those functions might provide the touch device with greater capabilities, to the possible advantage of the effectiveness and value of the touch device.